U.S. patent number 10,600,855 [Application Number 15/591,775] was granted by the patent office on 2020-03-24 for organic light-emitting display apparatus.
This patent grant is currently assigned to Samsung Display Co., Ltd.. The grantee listed for this patent is Samsung Display Co., Ltd.. Invention is credited to Deukjong Kim, Hagyeong Song.
United States Patent |
10,600,855 |
Song , et al. |
March 24, 2020 |
Organic light-emitting display apparatus
Abstract
In an organic light-emitting display apparatus comprising a
plurality of pixels, at least one of the plurality of pixels
includes a first conductive layer over a substrate, a first organic
insulating layer over the first conductive layer, the first organic
insulating layer comprising a first opening exposing a part of the
first conductive layer, a second conductive layer over the first
organic insulating layer, the second conductive layer contacting
the part of the first conductive layer exposed through the first
opening, a first inorganic insulating layer over the first organic
insulating layer to cover the second conductive layer, the first
inorganic insulating layer comprising a second opening exposing at
least a part of the first organic insulating layer, and a second
organic insulating layer over the first inorganic insulating layer,
the second organic insulating layer contacting the first organic
insulating layer through the second opening.
Inventors: |
Song; Hagyeong (Yongin-si,
KR), Kim; Deukjong (Yongin-si, KR) |
Applicant: |
Name |
City |
State |
Country |
Type |
Samsung Display Co., Ltd. |
Yongin-si, Gyeonggi-do |
N/A |
KR |
|
|
Assignee: |
Samsung Display Co., Ltd.
(KR)
|
Family
ID: |
60418974 |
Appl.
No.: |
15/591,775 |
Filed: |
May 10, 2017 |
Prior Publication Data
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Document
Identifier |
Publication Date |
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US 20170345883 A1 |
Nov 30, 2017 |
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Foreign Application Priority Data
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May 31, 2016 [KR] |
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10-2016-0067749 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
G09G
3/3225 (20130101); G09G 3/3233 (20130101); H01L
27/3258 (20130101); H01L 27/3248 (20130101); G09G
2330/10 (20130101); G09G 2300/0426 (20130101) |
Current International
Class: |
H01L
27/32 (20060101); G09G 3/3225 (20160101); G09G
3/3233 (20160101) |
Field of
Search: |
;257/40 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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10-2006-0055050 |
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May 2006 |
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KR |
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10-2006-0055211 |
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May 2006 |
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KR |
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10-2008-0057379 |
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Jun 2008 |
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KR |
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10-2014-0114312 |
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Sep 2014 |
|
KR |
|
10-2015-0070855 |
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Jun 2015 |
|
KR |
|
Primary Examiner: Erdem; Fazli
Attorney, Agent or Firm: Innovation Counsel LLP
Claims
What is claimed is:
1. An organic light-emitting display apparatus comprising a
plurality of pixels, wherein at least one of the plurality of
pixels comprises: a first conductive layer over a substrate; a
first organic insulating layer over the first conductive layer, the
first organic insulating layer comprising a first opening exposing
a part of the first conductive layer; a second conductive layer
over the first organic insulating layer, the second conductive
layer contacting the part of the first conductive layer exposed
through the first opening; a first inorganic insulating layer over
the first organic insulating layer to cover the second conductive
layer, the first inorganic insulating layer comprising a second
opening exposing at least a part of the first organic insulating
layer; and a second organic insulating layer over the first
inorganic insulating layer, the second organic insulating layer
being provided in one-piece, being formed of a same material,
overlapping at least a center of the second conductive layer and
contacting the first organic insulating layer through the second
opening.
2. The organic light-emitting display apparatus of claim 1, further
comprising a second inorganic insulating layer over the substrate
to cover the first conductive layer, wherein the second inorganic
insulating layer comprises a third opening exposing a part of the
first conductive layer, and the second conductive layer contacts
the part of the first conductive layer exposed through the first
opening and the third opening.
3. The organic light-emitting display apparatus of claim 2, wherein
the second inorganic insulating layer and the first inorganic
insulating layer respectively contact the first conductive layer
and the second conductive layer, the first organic insulating layer
is separated by the second inorganic insulating layer from the
first conductive layer, and the second organic insulating layer is
separated by the first inorganic insulating layer from the second
conductive layer.
4. The organic light-emitting display apparatus of claim 2, wherein
the first inorganic insulating layer and the second inorganic
insulating layer include silicon nitride (SiNx), and the first
organic insulating layer and the second organic insulating layer
include polyimide (PI).
5. The organic light-emitting display apparatus of claim 2, wherein
an edge of the first opening surrounds an edge of the third
opening, and the third opening is arranged inside the first
opening.
6. The organic light-emitting display apparatus of claim 1, further
comprising a thin film transistor comprising an active layer which
comprises a source region, a drain region, and a channel region
connecting the source region and the drain region, and a gate
electrode over the active layer to be insulated from the active
layer, wherein the first conductive layer is electrically connected
to the source region or the drain region.
7. The organic light-emitting display apparatus of claim 1, wherein
the first inorganic insulating layer further comprises a fourth
opening exposing a part of the second conductive layer, and the
second organic insulating layer comprises a fifth opening exposing
the part of the second conductive layer that is exposed by the
fourth opening.
8. The organic light-emitting display apparatus of claim 7, wherein
an edge of the fifth opening surrounds an edge of the fourth
opening, and the fourth opening is arranged inside the fifth
opening.
9. The organic light-emitting display apparatus of claim 7, further
comprising: a pixel electrode contacting the second conductive
layer through the fourth opening and the fifth opening; an
intermediate layer over the pixel electrode, the intermediate layer
comprising a light-emitting layer; and a counter electrode over the
intermediate layer.
10. The organic light-emitting display apparatus of claim 1,
further comprising: a lower power supply line on a same layer as
the first conductive layer; and an upper power supply line on a
same layer as the second conductive layer.
11. The organic light-emitting display apparatus of claim 10,
wherein the lower power supply line and the upper power supply line
are electrically connected to each other via a contact hole
included in the first organic insulating layer and the second
inorganic insulating layer.
12. The organic light-emitting display apparatus of claim 10,
wherein the first inorganic insulating layer entirely covers the
upper power supply line, and the second opening corresponds to a
space between the second conductive layer and the upper power
supply line.
13. The organic light-emitting display apparatus of claim 1,
wherein the second opening comprises a plurality of openings
arranged in an area adjacent to the second conductive layer.
14. The organic light-emitting display apparatus of claim 1,
wherein the second conductive layer comprises a first layer
including titanium (Ti), a second layer including aluminum (Al),
and a third layer including titanium (Ti).
15. An organic light-emitting display apparatus comprising a
plurality of pixels, wherein at least one of the plurality of
pixels comprises: a first conductive layer over a substrate; a
lower power supply line on a same layer as the first conductive
layer and spaced apart from the first conductive layer; a first
organic insulating layer over the first conductive layer and the
lower power supply line, the first organic insulating layer
comprising a first opening exposing a part of the first conductive
layer and a second opening exposing a part of the lower power
supply line; a second conductive layer over the first organic
insulating layer, the second conductive layer contacting the part
of the first conductive layer exposed through the first opening; an
upper power supply line on a same layer as the second conductive
layer, the upper power supply line contacting the part of the lower
power supply line through the second opening; a first inorganic
insulating layer over the first organic insulating layer to cover
the second conductive layer, the first inorganic insulating layer
comprising a first region covering the second conductive layer and
a second region covering the upper power supply line and spaced
apart from the first region; and a second organic insulating layer
over the first inorganic insulating layer, the second organic
insulating layer being provided in one-piece, being formed of a
same material, overlapping at least a center of the second
conductive layer and contacting the first organic insulating layer
between the first region and the second region of the first
inorganic insulating layer.
16. The organic light-emitting display apparatus of claim 15,
further comprising a second inorganic insulating layer over the
substrate to cover the first conductive layer and the lower power
supply line, the second inorganic insulating layer comprising a
third opening exposing a part of the first conductive layer and a
fourth opening exposing a part of the lower power supply line,
wherein the second conductive layer contacts the part of the first
conductive layer exposed through the first opening and the third
opening, and the upper power supply line contacts the part of the
lower power supply line exposed through the second opening and the
fourth opening.
17. The organic light-emitting display apparatus of claim 16,
wherein the first inorganic insulating layer and the second
inorganic insulating layer include silicon nitride (SiNx), and the
first organic insulating layer and the second organic insulating
layer include polyimide (PI).
18. The organic light-emitting display apparatus of claim 15,
wherein the second conductive layer comprises a first layer
including titanium (Ti), a second layer including aluminum (Al),
and a third layer including titanium (Ti).
19. The organic light-emitting display apparatus of claim 15,
further comprising a thin film transistor comprising an active
layer that comprises a source region, a drain region, and a channel
region connecting the source region and the drain region, and a
gate electrode over the active layer to be insulated from the
active layer, wherein the first conductive layer is electrically
connected to the source region or the drain region.
20. The organic light-emitting display apparatus of claim 15,
further comprising: a pixel electrode contacting the second
conductive layer; an intermediate layer over the pixel electrode,
the intermediate layer comprising a light-emitting layer; and a
counter electrode over the intermediate layer.
Description
CROSS-REFERENCE TO RELATED APPLICATION
This application claims the benefit of Korean Patent Application
No. 10-2016-0067749, filed on May 31, 2016, in the Korean
Intellectual Property Office, the disclosure of which is
incorporated herein in its entirety by reference.
BACKGROUND
1. Field
One or more embodiments relate to an organic light-emitting display
apparatus.
2. Description of the Related Art
Organic light-emitting display apparatuses may include thin film
transistors (TFTs), capacitors, and a plurality of wires. A
substrate on which an organic light-emitting display apparatus is
manufactured has a fine pattern of TFTs, capacitors, and wires. An
organic light-emitting display apparatus is operated by complicated
connections between the TFTs, the capacitors, and the wires.
As the demand for compact, high-resolution organic light-emitting
display apparatuses has increased, so has the demand for efficient
spatial arrangement, connection structure, and operating method of
TFTs, capacitors, and wires included in an organic light-emitting
display apparatus, and improved image quality.
SUMMARY
In a high-resolution organic light-emitting display apparatus, in
order to efficiently arrange a plurality of conductive layers such
as wires and electrodes in a limited space, a structure may be
employed, in which conductive layers are arranged spaced apart from
each other with an insulating layer therebetween and the conductive
layers are electrically connected to each other by forming a
contact hole in the insulating layer. In this case, an inorganic
insulating layer for protecting the conductive layers and an
organic insulating layer for planarizing the surfaces of the
conductive layers may be arranged between the conductive layers.
However, outgas generated in the organic insulating layer may not
be easily discharged outwardly due to the inorganic insulating
layer covering the organic insulating layer, and may be intensively
discharged through a certain area where the inorganic insulating
layer is discontinued. Accordingly, progressive dark spots are
generated by the outgas that is intensively discharged through a
certain area, thereby causing a pixel defect.
One or more embodiments include an organic light-emitting display
apparatus in which a pixel defect due to a progressive dark spot
may be removed or reduced by efficiently discharging outgas
generated from an organic insulating layer.
Additional aspects will be set forth in part in the description
which follows and, in part, will be apparent from the description,
or may be learned by practice of the presented embodiments.
According to one or more embodiments, in an organic light-emitting
display apparatus including a plurality of pixels, at least one of
the plurality of pixels includes a first conductive layer over a
substrate, a first organic insulating layer over the first
conductive layer, the first organic insulating layer including a
first opening exposing a part of the first conductive layer, a
second conductive layer over the first organic insulating layer,
the second conductive layer contacting the part of the first
conductive layer exposed through the first opening, a first
inorganic insulating layer over the first organic insulating layer
to cover the second conductive layer, the first inorganic
insulating layer including a second opening exposing at least a
part of the first organic insulating layer, and a second organic
insulating layer over the first inorganic insulating layer, the
second organic insulating layer contacting the first organic
insulating layer through the second opening.
The organic light-emitting display apparatus may further include a
second inorganic insulating layer over the substrate to cover the
first conductive layer, wherein the second inorganic insulating
layer includes a third opening exposing a part of the first
conductive layer, and the second conductive layer contacts the part
of the first conductive layer exposed through the first opening and
the third opening.
The second inorganic insulating layer and the first inorganic
insulating layer may respectively contact the first conductive
layer and the second conductive layer, the first organic insulating
layer may be separated by the second inorganic insulating layer
from the first conductive layer, and the second organic insulating
layer may be separated by the first inorganic insulating layer from
the second conductive layer.
The first inorganic insulating layer and the second inorganic
insulating layer may include silicon nitride (SiN.sub.x), and the
first organic insulating layer and the second organic insulating
layer may include polyimide (PI).
An area of the first opening may be greater than an area of the
third opening, and the third opening may be arranged inside the
first opening.
The organic light-emitting display apparatus may further include a
thin film transistor including an active layer which includes a
source region, a drain region, and a channel region connecting the
source region and the drain region, and a gate electrode over the
active layer to be insulated from the active layer, in which the
first conductive layer may be electrically connected to the source
region or the drain region.
The first inorganic insulating layer may further include a fourth
opening exposing a part of the second conductive layer, and the
second organic insulating layer may include a fifth opening
exposing the part of the second conductive layer that is exposed by
the fourth opening.
An area of the fifth opening may be greater than an area of the
fourth opening, and the fourth opening may be arranged inside the
fifth opening.
The organic light-emitting display apparatus may further include a
pixel electrode contacting the second conductive layer through the
fourth opening and the fifth opening, an intermediate layer over
the pixel electrode, the intermediate layer including a
light-emitting layer, and a counter electrode over the intermediate
layer.
The organic light-emitting display apparatus may further include a
lower power supply line on a same layer as the first conductive
layer, and an upper power supply line on a same layer as the second
conductive layer.
The lower power supply line and the upper power supply line may be
electrically connected to each other via a contact hole included in
the first organic insulating layer and the second inorganic
insulating layer.
The first inorganic insulating layer may entirely cover the upper
power supply line, and the second opening may correspond to a space
between the second conductive layer and the upper power supply
line.
The second opening may include a plurality of openings arranged in
an area adjacent to the second conductive layer.
The second conductive layer may include a first layer including
titanium (Ti), a second layer including aluminum (Al), and a third
layer including titanium (Ti).
According to one or more embodiments, in an organic light-emitting
display apparatus including a plurality of pixels, at least one of
the plurality of pixels includes a first conductive layer over a
substrate, a lower power supply line on a same layer as the first
conductive layer and spaced apart from the first conductive layer,
a first organic insulating layer over the first conductive layer
and the lower power supply line, the first organic insulating layer
including a first opening exposing a part of the first conductive
layer and a second opening exposing a part of the lower power
supply line, a second conductive layer over the first organic
insulating layer, the second conductive layer contacting the part
of the first conductive layer exposed through the first opening, an
upper power supply line on a same layer as the second conductive
layer, the upper power supply line contacting the part of the lower
power supply line through the second opening, a first inorganic
insulating layer over the first organic insulating layer, the first
inorganic insulating layer including a first region covering the
second conductive layer and a second region covering the upper
power supply line and spaced apart from the first region, and a
second organic insulating layer over the first inorganic insulating
layer, the second organic insulating layer contacting the first
organic insulating layer between the first region and the second
region of the first inorganic insulating layer.
The organic light-emitting display apparatus may further include a
second inorganic insulating layer over the substrate to cover the
first conductive layer and the lower power supply line, the second
inorganic insulating layer including a third opening exposing a
part of the first conductive layer and a fourth opening exposing a
part of the lower power supply line, and the second conductive
layer contacts the part of the first conductive layer exposed
through the first opening and the third opening, in which the upper
power supply line contacts the part of the lower power supply line
exposed through the second opening and the fourth opening.
The first inorganic insulating layer and the second inorganic
insulating layer may include silicon nitride (SiN.sub.x), and the
first organic insulating layer and the second organic insulating
layer may include polyimide (PI).
The second conductive layer may include a first layer including
titanium (Ti), a second layer including aluminum (Al), and a third
layer including titanium (Ti).
The organic light-emitting display apparatus may further include a
thin film transistor including an active layer that includes a
source region, a drain region, and a channel region connecting the
source region and the drain region, and a gate electrode over the
active layer to be insulated from the active layer, in which the
first conductive layer is electrically connected to the source
region or the drain region.
The organic light-emitting display apparatus may further include a
pixel electrode contacting the second conductive layer, an
intermediate layer over the pixel electrode, the intermediate layer
including a light-emitting layer, and a counter electrode over the
intermediate layer.
BRIEF DESCRIPTION OF THE DRAWINGS
These and/or other aspects will become apparent and more readily
appreciated from the following description of the embodiments,
taken in conjunction with the accompanying drawings in which:
FIG. 1 is an equivalent circuit diagram of a pixel of an organic
light-emitting display apparatus according to an embodiment;
FIG. 2 is a plan view schematically illustrating positions of a
plurality of thin film transistors and capacitors in the pixel of
FIG. 1;
FIG. 3 is a schematic plan view of a first conductive layer, a
second conductive layer, and a first inorganic insulating layer
included in the organic light-emitting display apparatus of FIG.
1;
FIG. 4 is a cross-sectional view taken along lines VIa-VIa' and
VIb-VIb' of FIG. 2;
FIG. 5 is a schematic cross-sectional view of an organic
light-emitting display apparatus according to another embodiment;
and
FIG. 6 is a schematic plan view of a partial structure of the
organic light-emitting display apparatus of FIG. 5.
DETAILED DESCRIPTION
Reference will now be made in detail to embodiments, examples of
which are illustrated in the accompanying drawings, wherein like
reference numerals refer to like elements throughout. In this
regard, the present embodiments may have different forms and should
not be construed as being limited to the descriptions set forth
herein. Accordingly, the embodiments are merely described below, by
referring to the figures, to explain aspects of the present
description.
As used herein, the term "and/or" includes any and all combinations
of one or more of the associated listed items. Expressions such as
"at least one of," when preceding a list of elements, modify the
entire list of elements and do not modify the individual elements
of the list.
It will be understood that when a component, such as a layer, a
film, a region, or a plate, is referred to as being "on" another
component, the component may be directly on the other component, or
intervening components may be present thereon. Sizes of components
in the drawings may be exaggerated or reduced for convenience of
explanation. In other words, since sizes and thicknesses of
components in the drawings are arbitrarily illustrated for
convenience of explanation, the following embodiments are not
limited thereto.
Although the accompanying drawings illustrate an active matrix (AM)
type organic light-emitting display apparatus having a 7Tr-1Cap
structure, that is, seven thin film transistors (TFTs) and one
capacitor are included in one pixel, the present inventive concept
is not limited thereto. Accordingly, a display apparatus may
include a plurality of TFTs and one or more capacitors in one
pixel, and may have various structures by further including a
separate wiring or omitting a wiring shown in the drawings. The
organic light-emitting display apparatus may include a plurality of
pixels, each pixel denoting a minimum unit for displaying an image.
The organic light-emitting display apparatus displays a desired
image through a combination of the pixels.
FIG. 1 is an equivalent circuit diagram of one pixel of an organic
light-emitting display apparatus according to an embodiment.
As illustrated in FIG. 1, one of a plurality of pixels of the
organic light-emitting display apparatus according to the present
embodiment may include a plurality of signal lines 121, 122, 123,
124, 176, 177, and 178, a plurality of TFTs T1, T2, T3, T4, T5, T6,
and T7 connected to the signal lines, a storage capacitor Cst, and
an organic light-emitting device (OLED). The signal lines 121, 122,
123, 124, 176, 177, and 178 may be shared by other pixels.
The TFT may include a driving TFT T1, a switching TFT T2, a
compensation TFT T3, an initialization TFT T4, an operation control
TFT T5, a light emission control TFT T6, and a bypass TFT T7.
The signal lines 121, 122, 123, 124, 176, 177, and 178 may include
the scan line 121 for transmitting a scan signal Sn, the previous
scan line 122 for transmitting a previous scan signal Sn-1 to the
initialization TFT T4 and the bypass TFT T7, the light emission
control line 123 for transmitting a light emission control signal
En to the operation control TFT T5 and the light emission control
TFT T6, the data line 176 for transmitting a data signal Dm
crossing the scan line 121, the power supply lines 177 and 178 for
transmitting a drive voltage ELVDD, which are substantially
parallel to the data line 176, and an initialization voltage line
124 for transmitting an initialization voltage Vint to initialize
the driving TFT T1. The power supply lines 177 and 178 may include
a lower power supply line 177 and an upper power supply line 178
arranged on different layers. The lower power supply line 177 and
the upper power supply line 178 may be electrically connected to
each other, which is described later.
A gate electrode G1 of the driving TFT T1 is connected to a first
storage conductive plate 125a of the storage capacitor Cst. A
source electrode S1 of the driving TFT T1 is connected to the power
supply lines 177 and 178 via the operation control TFT T5. A drain
electrode D1 of the driving TFT T1 is electrically connected to a
pixel electrode of the OLED via the light emission control TFT T6.
The driving TFT T1 receives the data signal Dm and supplies a light
emission current I.sub.OLED to the OLED, according to a switching
operation of the switching TFT T2.
A gate electrode G2 of the switching TFT T2 is connected to the
scan line 121. A source electrode S2 of the switching TFT T2 is
connected to the data line 176. A drain electrode D2 of the
switching TFT T2 is connected to the source electrode S1 of the
driving TFT T1 and connected to the power supply lines 177 and 178
via the operation control TFT T5. The switching TFT T2 is turned on
by the scan signal Sn received through the scan line 121 and
performs a switching operation of transmitting the data signal Dm
received through the data line 176 to the source electrode S1 of
the driving TFT T1.
A gate electrode G3 of the compensation TFT T3 is connected to the
scan line 121. A source electrode S3 of the compensation TFT T3 is
connected to the drain electrode D1 of the driving TFT T1 and
connected to a pixel electrode 191 (see FIG. 4) of the OLED via the
light emission control TFT T6. A drain electrode D3 of the
compensation TFT T3 is connected to the first storage conductive
plate 125a of the storage capacitor Cst, a drain electrode D4 of
the initialization TFT T4, and the gate electrode G1 of the driving
TFT T1. The compensation TFT T3 is turned on by the scan signal Sn
received through the scan line 121 to electrically connect the gate
electrode G1 and the drain electrode D1 of the driving TFT T1,
thereby diode-connecting the driving TFT T1.
A gate electrode G4 of the initialization TFT T4 is connected to
the previous scan line 122. A source electrode S4 of the
initialization TFT T4 is connected to a drain electrode D7 of the
bypass TFT T7 and the initialization voltage line 124. A drain
electrode D4 of the initialization TFT T4 is connected to the first
storage conductive plate 125a of the storage capacitor Cst, the
drain electrode D3 of the compensation TFT T3, and the gate
electrode G1 of the driving TFT T1. The initialization TFT T4 is
turned on by the previous scan signal Sn-1 received through the
previous scan line 122 and performs an initialization operation of
initializing a voltage of the gate electrode G1 of the driving TFT
T1 by transmitting the initialization voltage Vint to the gate
electrode G1 of the driving TFT T1.
A gate electrode G5 of the operation control TFT T5 is connected to
the light emission control line 123. A source electrode S5 of the
operation control TFT T5 is connected to the power supply lines 177
and 178. A drain electrode D5 of the operation control TFT T5 is
connected to the source electrode S1 of the driving TFT T1 and the
drain electrode D2 of the switching TFT T2.
A gate electrode G6 of the light emission control TFT T6 is
connected to the light emission control line 123. A source
electrode S6 of the light emission control TFT T6 is connected to
the drain electrode D1 of the driving TFT T1 and the source
electrode S3 of the compensation TFT T3. A drain electrode D6 of
the light emission control TFT T6 is electrically connected to the
source electrode S7 of the bypass TFT T7 and the pixel electrodes
191 of the OLED. The operation control TFT T5 and the light
emission control TFT T6 are simultaneously turned on by the light
emission control signal En received through the light emission
control line 123 to transmit the drive voltage ELVDD to the OLED,
thereby having the light emission current I.sub.OLED flowing in the
OLED.
A gate electrode G7 of the bypass TFT T7 is connected to the
previous scan line 122. The source electrode S7 of the bypass TFT
T7 is connected to the drain electrode D6 of the light emission
control TFT T6 and the pixel electrode 191 of the OLED. The drain
electrode D7 of the bypass TFT T7 is connected to the
initialization voltage line 124. The bypass TFT T7 receives the
previous scan signal Sn-1 through the previous scan line 122 at its
gate electrode G7. The previous scan signal Sn-1 is a voltage of a
certain level enough to turn off the bypass TFT T7. In a state in
which the bypass TFT T7 is turned off, part of a drive current
I.sub.d passes through the bypass TFT T7 as a bypass current
I.sub.bp.
When displaying a black image, a minimum current of the driving TFT
T1 flows as a drive current. As such, the OLED emits light, and the
black image is not displayed well. The minimum current of the
driving TFT T1 denotes a current under a condition in which the
driving TFT T1 is turned off because a gate-source voltage V.sub.GS
of the driving TFT T1 is less than a threshold voltage Vth.
Accordingly, in order to prevent the OLED from emitting light even
when the minimum current flows as the drive current, the bypass TFT
T7 may allow part of the current I.sub.d flowing out from the
driving TFT T1 to flow along another current path other than a
current path toward the OLED, as a the bypass current I.sub.bp. As
such, as a current less than the minimum drive current, for
example, about 10 pA or less, is transmitted to the OLED to turn
off the driving TFT T1, the OLED is prevented from emitting light
or a degree of light emission is reduced so that a black image is
implemented.
When the minimum drive current to display a black image flows, the
bypass current I.sub.bp is branched from the minimum drive current,
and thus, whether the OLED emits light or a degree of light
emission is greatly affected. However, when a large drive current
to display a general image or a white image flows, the degree of
light emission in the OLED may be hardly affected by the bypass
current I.sub.bp. Accordingly, when a drive current to display a
black image flows, the light emission current I.sub.OLED of the
OLED, which is reduced from the drive current I.sub.d by a current
amount of the bypass current I.sub.bp that flows through the bypass
TFT T7, has a current amount of a level to display a blacker black
image. Accordingly, as a more accurate black brightness image is
implemented by using the bypass TFT T7, a contrast ratio may be
improved.
Although FIG. 1 illustrates a case in which the initialization TFT
T4 and the bypass TFT T7 are connected to the previous scan line
122, the present inventive concept is not limited thereto. In
another embodiment, the initialization TFT T4 is connected to the
previous scan line 122 and driven by the previous scan signal Sn-1,
and the bypass TFT T7 is connected to a separate wire and may be
driven by a signal transmitted through the wire.
A second storage conductive plate 127 of the storage capacitor Cst
is connected to the power supply lines 177 and 178. A counter
electrode 193 (see FIG. 4) of the OLED is connected to a common
voltage ELVSS. Accordingly, the OLED may display an image by
receiving the light emission current I.sub.OLED from the driving
TFT T1 and emitting light.
Although FIG. 1 illustrates that each of the compensation TFT T3
and the initialization TFT T4 has a dual-gate electrode, the
present inventive concept is not limited thereto. For example, each
of the compensation TFT T3 and the initialization TFT T4 may have a
single-gate electrode. Also, various modifications are possible,
for example, at least one of the TFTs T1, T2, T5, T6, and T7 other
than the compensation TFT T3 and the initialization TFT T4 may have
a dual-gate electrode.
A detailed operation of one pixel of an organic light-emitting
display apparatus is schematically described below.
First, the previous scan signal Sn-1 of a low level is supplied
through the previous scan line 122 for an initialization period.
Then, in response to the previous scan signal Sn-1 of a low level,
the initialization TFT T4 is turned on so that the initialization
voltage Vint from the initialization voltage line 124 is
transmitted to the gate electrode G1 of the driving TFT T1 via the
initialization TFT T4. Accordingly, the driving TFT T1 is
initialized by the initialization voltage Vint.
Then, the scan signal Sn of a low level is supplied through the
scan line 121 during a data programming period. Next, in response
to the scan signal Sn of a low level, the switching TFT T2 and the
compensation TFT T3 are turned on. Accordingly, the driving TFT T1
is diode-connected by the compensation TFT T3 that is turned on,
and is biased in a forward direction. Then, a compensation voltage
Dm+Vth, which is reduced by the threshold voltage Vth (i.e., Vth is
a negative (-) value) of the driving TFT T1 from the data signal Dm
supplied through the data line 176, is applied to the gate
electrode G1 of the driving TFT T1. The drive voltage ELVDD and the
compensation voltage Dm+Vth are applied to both ends of the storage
capacitor Cst, and thus, electric charges corresponding to a
voltage difference between both ends is stored in the storage
capacitor Cst.
During a light emission period, the light emission control signal
En supplied through the light emission control line 123 is changed
from a high level to a low level. Then, the operation control TFT
T5 and the light emission control TFT T6 are turned on by the light
emission control signal En of a low level during the light emission
period. The drive current I.sub.d that is determined by the voltage
difference between the voltage of the gate electrode G1 of the
driving TFT T1 and the drive voltage ELVDD is generated. The light
emission current I.sub.d corresponding to the difference between
the drive current I.sub.d and the bypass current I.sub.bp is
supplied to the OLED through the light emission control TFT T6.
During the light emission period, the gate-source voltage V.sub.GS
of the driving TFT T1 is maintained to be "(Dm+Vth)-ELVDD" by the
storage capacitor Cst. According to a current-voltage relationship
of the driving TFT T1, because the light emission current
I.sub.OLED is proportional to "(Dm-ELVDD).sup.2" that is the square
of a value obtained by deducting the threshold voltage Vth from the
gate-source voltage V.sub.GS, the light emission current I.sub.OLED
is determined independent of the threshold voltage Vth of the
driving TFT T1.
According to one embodiment, although the TFTs T1, T2, T3, T4, T5,
T6, and T7 may be p-channel field effect transistors, the present
inventive concept is not limited thereto, and at least some of the
TFTs T1, T2, T3, T4, T5, T6, and T7 may be n-channel field effect
transistors.
In the following description, a detailed structure of one pixel of
the organic light-emitting display apparatus of FIG. 1 is described
with reference to FIG. 2.
FIG. 2 is a plan view schematically illustrating positions of a
plurality of thin film transistors and capacitors in the pixel of
FIG. 1. FIG. 2 illustrates arrangements of semiconductor layers and
conductive layers. An insulating layer may be interposed between a
semiconductor layer (conductive layer) and a conductive layer
arranged in different layers. Contact holes are formed in parts of
the insulating layers, and thus, the conductive layers arranged in
different layers may be electrically connected to each other in a
vertical direction.
A pixel of an organic light-emitting display apparatus according to
the present embodiment may include the scan line 121 the previous
scan line 122, the light emission control line 123, and the
initialization voltage line 124, which are arranged in a row
direction, and through which the scan signal Sn, the previous scan
signal Sn-1, the light emission control signal En, and the
initialization voltage Vint are respectively applied. The pixel of
an organic light-emitting display apparatus according to the
present embodiment may include the data line 176 and the power
supply lines 177 and 178, which intersect the scan line 121, the
previous scan line 122, the light emission control line 123, and
the initialization voltage line 124 and respectively apply the data
signal Dm and the drive voltage ELVDD to the pixel.
Also, the pixel may include the driving TFT T1, the switching TFT
T2, the compensation TFT T3, the initialization TFT T4, the
operation control TFT T5, the light emission control TFT T6, the
bypass TFT T7, the storage capacitor Cst, and the OLED (see FIG.
4).
The driving TFT T1, the switching TFT T2, the compensation TFT T3,
the initialization TFT T4, the operation control TFT T5, the light
emission control TFT T6, and the bypass TFT T7 are formed along an
active layer that may have a curved shape in various forms. The
active layer may include a driving active layer corresponding to
the driving TFT T1, a switching active layer corresponding to the
switching TFT T2, a compensation active layer corresponding to the
compensation TFT T3, an initialization active layer corresponding
to the initialization TFT T4, an operation control active layer
ACTe (see FIG. 4) corresponding to the operation control TFT T5, a
light emission control active layer ACTf (see FIG. 4) corresponding
to the light emission control TFT T6, and a bypass active layer
corresponding to the bypass TFT T7.
The active layer may include polysilicon. The active layer may
include, for example, a channel region that is not doped with
impurities and thus has semiconductor properties, and a source
region and a drain region that are located at opposite sides of the
channel region and doped with impurities and thus have
conductivity. The impurities may vary according to the type of a
TFT, and N-type impurities or P-type impurities may be used.
The source region or the drain region, which is formed by doping,
may be interpreted to be a source electrode or a drain electrode of
a TFT. In other words, for example, a driving source electrode may
correspond to a driving source region 133a that is doped with
impurities in vicinity of a driving channel region 131a of the
driving active layer, and a driving drain electrode may correspond
to a driving drain region 135a that is doped with impurities in
vicinity of the driving channel region 131a. Also, parts of the
active layer corresponding to an area between TFTs are doped with
impurities and may be wires electrically connecting the TFTs.
A pixel of an organic light-emitting display apparatus according to
the present embodiment may include the storage capacitor Cst. The
storage capacitor Cst may include the first storage conductive
plate 125a and the second storage conductive plate 127, which are
arranged facing each other. A second insulating layer 142 is
interposed between the first storage conductive plate 125a and the
second storage conductive plate 127. According to an embodiment,
the first storage conductive plate 125a may simultaneously function
as a driving gate electrode 125a. In other words, the driving gate
electrode 125a and the first storage conductive plate 125a may be
one body.
The first storage conductive plate 125a may have an island shape
isolated from an adjacent pixel. The first storage conductive plate
125a may be formed of the same material and on the same layer as
the scan line 121, the previous scan line 122, and the light
emission control line 123.
For reference, a switching gate electrode 125b and compensation
gate electrodes 125c1 and 125c2 may be parts of the scan line 121
intersecting the active layer or parts protruding from the scan
line 121. Initialization gate electrodes 125d1 and 125d2 and a
bypass gate electrode 125g are parts of the previous scan line 122
intersecting the active layer or parts protruding from the previous
scan line 122. An operation control gate electrode 125e and a light
emission control gate electrode 125f may be parts of the light
emission control line 123 intersecting the active layer or parts
protruding from the light emission control line 123.
The second storage conductive plate 127 may be connected to each
other in adjacent pixels, and may be formed of the same material
and on the same layer as the initialization voltage line 124 and/or
a shield layer 126. A storage opening 127h may be formed in the
second storage conductive plate 127. Accordingly, the first storage
conductive plate 125a and a compensation drain region 135c of the
compensation TFT T3 may be electrically connected to each other by
a connection member 174 that is described later. The second storage
conductive plate 127 may be connected to the lower power supply
line 177 via a contact hole 168 formed in an interlayer insulating
layer 160.
The driving TFT T1 may include the driving active layer and the
driving gate electrode 125a. The driving active layer may include
the driving source region 133a, the driving drain region 135a, and
the driving channel region 131a connecting the driving source
region 133a and the driving drain region 135a, The driving gate
electrode 125a may also perform a function of the first storage
conductive plate 125a as described above. The driving channel
region 131a of the driving active layer overlaps the gate electrode
125a in plan view. The driving source region 133a and the driving
drain region 135a are located in opposite directions with respect
to the driving channel region 131a. The driving source region 133a
of the driving TFT T1 is connected to a switching drain region 135b
and an operation control drain region 135e, which are described
later. The driving drain region 135a is connected to a compensation
source region 133c and a light emission control source region 133f,
which are described later.
The switching TFT T2 may include the switching active layer and the
switching gate electrode 125b. The switching active layer may
include a switching channel region 131b, a switching source region
133b, and the switching drain region 135b. The switching source
region 133b may be electrically connected to the data line 176 via
a contact hole 164 formed in a first insulating layer 141, the
second insulating layer 142, and the interlayer insulating layer
160. The switching TFT T2 is used as a switching element to select
a pixel to emit light. The switching gate electrode 125b is
connected to the scan line 121. The switching source region 133b is
connected to the data line 176 as described above. The switching
drain region 135b is connected to the driving TFT T1 and the
operation control TFT T5.
The compensation TFT T3 may include the compensation active layer
and the compensation gate electrodes 125c1 and 125c2. The
compensation active layer may include compensation channel regions
131c1, 131c2, and 131c3, the compensation source region 133c, and
the compensation drain region 135c. The compensation gate
electrodes 125c1 and 125c2, which form a dual-gate electrode
including the first compensation gate electrode 125c1 and the
second compensation gate electrode 125c2, may prevent or reduce
generation of a leakage current. The compensation drain region 135c
of the compensation TFT T3 may be connected to the first storage
conductive plate 125a through the connection member 174. The
compensation channel regions 131c1, 131c2, and 131c3 may include a
part 131c1 corresponding to the first compensation gate electrode
125c1, a part 131c3 corresponding to the second compensation gate
electrode 125c2, and a part 131c2 between the parts 131c1 and
131c3. The shield layer 126 that is formed of the same material and
on the same layer as the initialization voltage line 124 and the
second storage conductive plate 127 is located on the part 131c2
between the parts 131c1 and 131c3. The shield layer 126 may be
connected to the lower power supply line 177 via a contact hole 169
formed in the interlayer insulating layer 160. Since the part 131c2
between the parts 131c1 and 131c3 is a conductive part doped with
impurities, when the shield layer 126 does not exist, the part
131a2 and the data line 176 arranged adjacent thereto may formed a
parasitic capacitor, Since the data line 176 applies data signals
having different intensities according to brightness to be
implemented in a pixel, capacitance of the parasitic capacitor may
be changed. The compensation TFT T3 is electrically connected to
the driving TFT T1. As the capacitance of the parasitic capacitor
formed in the compensation TFT T3 is changed, the drive current
I.sub.d and the light emission current I.sub.OLED are changed.
Consequently, the brightness of light emitted from the pixel may be
changed.
However, when the shield layer 126 connected to the lower power
supply line 177 and applying a constant voltage is arranged on the
part 131c2 between the parts 131c1 and 131c3, the part 131c2 and
the shield layer 126 may substantially form a parasitic capacitor
having a certain capacitance. Since the parasitic capacitor formed
by the part 131c2 and the shield layer 126 has a very large
capacitance compared to the parasitic capacitor formed by the part
131c2 and the data line 176, a change in the capacitance of the
parasitic capacitor formed by the part 131c2 and the shield layer
126 according to a change of the data signal applied to the data
line 176 may be very small, compared to the capacitance of the
parasitic capacitor formed by the part 131c2 and the shield layer
126, so as to be maintained at a negligible level. Accordingly, a
change in the brightness of light emitted from a pixel, which may
be generated by a change in the capacitance of the parasitic
capacitor, may be prevented or reduced.
The connection member 174 may be formed of the same material and on
the same layer as the data line 176 and the lower power supply line
177. One end of the connection member 174 is connected to the
compensation drain region 135c and an initialization drain region
135d via a contact hole 166 formed in the first insulating layer
141, the second insulating layer 142, and the interlayer insulating
layer 160. The other end of the connection member 174 is connected
to the first storage conductive plate 125a via a contact hole 167
formed in the second insulating layer 142 and the interlayer
insulating layer 160. The other end of the connection member 174
may be connected to the first storage conductive plate 125a via the
storage opening 127h formed in the second storage conductive plate
127. The initialization TFT T4 may include the initialization
active layer and the initialization gate electrodes 125d1 and
125d2. The initialization active layer may include initialization
channel regions 131d1, 131d2, and 131d3, an initialization source
region 133d, and the initialization drain region 135d. The
initialization gate electrodes 125d1 and 125d2, which form a
dual-gate electrode including a first initialization gate electrode
125d1 and a second initialization gate electrode 125d2, may prevent
or reduce generation of a leakage current. The initialization
channel regions 131d1, 131d2, and 131d3 may include a region 131d3
corresponding to the first initialization gate electrode 125d1, a
region 131d1 corresponding to the second initialization gate
electrode 125d2, and a region 131d2 therebetween.
The initialization source region 133d is connected to the
initialization voltage line 124 through an initialization
connection line 173. One end of the initialization connection line
173 is connected to the initialization voltage line 124 via a
contact hole 161 formed in the second insulating layer 142 and the
interlayer insulating layer 160. The other end of the
initialization connection line 173 may be connected to the
initialization source region 133d via a contact hole 162 formed in
the first insulating layer 141, the second insulating layer 142,
and the interlayer insulating layer 160.
The operation control TFT T5 may include the operation control
active layer ACTe of FIG. 4 and the operation control gate
electrode 125e. The operation control active layer ACTe may include
an operation control channel region 131e, an operation control
source region 133e, and the operation control drain region 135e.
The operation control source region 133e may be electrically
connected to the lower power supply line 177 via a contact hole 165
formed in the first insulating layer 141, the second insulating
layer 142, and the interlayer insulating layer 160.
The light emission control TFT T6 may include the light emission
control active layer ACTf and the light emission control gate
electrode 125f. The light emission control active layer ACTf may
include a light emission control channel region 131f, the light
emission control source region 133f, and a light emission control
drain region 135f. A first conductive layer 175 is arranged on the
light emission control TFT T6. The first conductive layer 175 may
be connected to the light emission control drain region 135f of the
light emission control active layer ACTf via a contact hole 163
formed in the first insulating layer 141, the second insulating
layer 142, and the interlayer insulating layer 160. The first
conductive layer 175 may be formed of the same material and on the
same layer as the data line 176 and the lower power supply line
177. The first conductive layer 175 is electrically connected to a
second conductive layer 179 as described later, and consequently,
electrically connected to the pixel electrode 191 of the OLED.
The bypass TFT T7 may include the bypass active layer and the
bypass gate electrode 125g. The bypass active layer may include a
bypass source region 133g, a bypass drain region 135g, and a bypass
channel region 131g. The bypass drain region 135g is connected to
the initialization source region 133d of the initialization TFT T4
and thus connected to the initialization voltage line 124 through
the initialization connection line 173. The bypass source region
133g is electrically connected to the pixel electrode 191 of the
OLED.
The second conductive layer 179 is arranged on the first conductive
layer 175. The second conductive layer 179 may be connected to the
first conductive layer 175 via a contact hole 183 formed in a first
organic insulating layer 171 (see FIG. 4) and a second inorganic
insulating layer 172 (see FIG. 4). The pixel electrode 191 of the
OLED is arranged on the second conductive layer 179. The pixel
electrode 191 may be connected to the second conductive layer 179
via a contact hole 185 formed in a second organic insulating layer
181 and in a first inorganic insulating layer 182 (see FIG. 4)
located between the second conductive layer 179 and the pixel
electrode 191. In other words, the first conductive layer 175 and
the second conductive layer 179 may be intermediate connection
layers to connect the light emission control drain region 135f of
the light emission control active layer ACTf and the pixel
electrode 191. The second conductive layer 179 may be formed of the
same material and on the same layer as the upper power supply line
178. The upper power supply line 178 may be connected to the lower
power supply line 177 via a contact hole 187 formed in the second
organic insulating layer 181 and the first inorganic insulating
layer 182. The power supply lines 177 and 178 may include the lower
power supply line 177 and the upper power supply line 178, which
are electrically connected to each other. In the above structure,
as a space in the pixel occupied by the power supply lines 177 and
178 is reduced, resistance of the power supply lines 177 and 178
may be reduced. In other words, as a voltage drop of the power
supply lines 177 and 178 is decreased, quality of an image may be
improved.
FIG. 3 is a schematic plan view of a first conductive layer, a
second conductive layer, and a first inorganic insulating layer
included in the organic light-emitting display apparatus of FIG. 1.
FIG. 4 is a cross-sectional view taken along lines VIa-VIa' and
VIb-VIb' of FIG. 2.
Referring to FIGS. 3 and 4, an organic light-emitting display
apparatus according to an embodiment may include a plurality of
pixels. At least one of the pixels may include the first conductive
layer 175 arranged over a substrate 110, a first organic insulating
layer 171 including a first opening 171h1 exposing a part of the
first conductive layer 175, the second conductive layer 179
arranged over the first organic insulating layer 171 and contacting
the part of first conductive layer 175 exposed through the first
opening 171h1, the first inorganic insulating layer 182 arranged
over the first organic insulating layer 171 to cover the second
conductive layer 179 and having a second opening 182h2 exposing at
least a part of the first organic insulating layer 171, and the
second organic insulating layer 181 arranged over the first
inorganic insulating layer 182 and contacting the first organic
insulating layer 171 via the second opening 182h2.
The substrate 110 may be formed of various materials such as a
glass material, a metal material, or a plastic material. According
to an embodiment, the substrate 110 may be a flexible substrate.
For example, the substrate 110 may include polymer resin such as
polyethersulphone (PES), polyacrylate (PAR), polyetherimide (PEI),
polyethylenenapthalate (PEN), polyethyleneterepthalate (PET),
polyphenylenesulfide (PPS), polyallylate, polyimide (PI),
polycarbonate (PC), or cellulose acetate propionate (CAP).
The substrate 110 may include a display area configured to display
an image and a non-display area outside the display area. A
plurality of pixels may be arranged in the display area. FIGS. 2
and 3 illustrate one pixel arranged in the display area of the
substrate 110, The TFTs T1, T2, T3, T4, T5, T6, and T7 (see FIG. 2)
and the OLED connected to at least one of the TFTs may be arranged
over the substrate 110. In the following description, the
arrangement of the first conductive layer 175, the lower power
supply line 177 arranged on the same layer as the first conductive
layer 175, the second conductive layer 179, the upper power supply
line 178 arranged on the same layer as the second conductive layer
179 and the first inorganic insulating layer 182 covering the above
elements is described below with reference to FIGS. 3 and 4.
Referring to FIGS. 3 and 4, the operation control TFT T5 and the
light emission control TFT T6 are arranged over the substrate 110.
Other TFTs included in one pixel are not illustrated in FIG. 4. The
operation control TFT T5 and the light emission control TFT T6 are
mainly described in a partial cross-sectional structure of FIG. 2.
The operation control TFT T5 may include the operation control
active layer ACTe and the operation control gate electrode 125e.
The light emission control TFT T6 may include the light emission
control active layer ACTf and the light emission control gate
electrode 125f. The active layers ACTe and ACTf may include
amorphous silicon, polycrystalline silicon, or an organic
semiconductor material, and include the source regions 133e and
133f, the drain regions 135e and 135f, and the channel region 131e
and 131f connecting the source regions 133e and 133f and the drain
regions 135e and 135f. The gate electrodes 125e and 125f are
respectively arranged above the active layers ACTe and ACTf. The
source regions 133e and 133f and the drain regions 135e and 135f
are electrically communicated according to signals applied to the
gate electrodes 125e and 125f. The gate electrodes 125e and 125f
may be formed of at least one of, for example, aluminum (Al),
platinum (Pt), palladium (Pd), silver (Ag), magnesium (Mg), gold
(Au), nickel (Ni), neodymium (Nd), iridium (Ir), chromium (Cr),
lithium (Li), calcium (Ca), molybdenum (Mo), titanium (Ti),
tungsten (W), and copper (Cu), in a single layer or as multilayers,
depending on factors such as close contact with an adjacent layer,
surface planarization of a stacked layer, and processability.
To secure insulation of the active layers ACTe and ACTf and the
gate electrodes 125e and 125f, the first insulating layer 141
including an inorganic material such as silicon oxide, silicon
nitride, and/or silicon oxynitride may be interposed between the
active layers ACTe and ACTf and the gate electrodes 125e and 125f.
In addition, the second insulating layer 142 including an inorganic
material such as silicon oxide, silicon nitride, and/or silicon
oxynitride may be arranged over the gate electrodes 125e and 125f.
The interlayer insulating layer 160 may be arranged over the second
insulating layer 142. The interlayer insulating layer 160 may
include an inorganic material such as silicon oxide, silicon
nitride, and/or silicon oxynitride.
A buffer layer 111 including an inorganic material such as silicon
oxide, silicon nitride, and/or silicon oxynitride may be interposed
between the TFTs T5 and T6 and the substrate 110. The buffer layer
111 may improve smoothness of an upper surface of the substrate 110
or may prevent or reduce intrusion of impurities from the substrate
110 into the active layers ACTe and ACTf.
The first conductive layer 175 and the lower power supply line 177
are arranged over the interlayer insulating layer 160. The first
conductive layer 175 and the lower power supply line 177 may be
formed of at least one material of, for example, aluminum (Al),
platinum (Pt), palladium (Pd), silver (Ag), magnesium (Mg), gold
(Au), nickel (Ni), neodymium (Nd), iridium (Ir), chromium (Cr),
lithium (Li), calcium (Ca), molybdenum (Mo), titanium (Ti),
tungsten (W), and copper (Cu), in a single layer or as multilayers,
depending on factors such as conductivity. For example, the first
conductive layer 175 and the lower power supply line 177 may be a
stacked structure of titanium (Ti)/aluminum (AO/titanium (Ti). The
first conductive layer 175 may be electrically connected to the
light emission control drain region 135f of the light emission
control active layer ACTf via the contact hole 163 formed in the
first insulating layer 141, the second insulating layer 142, and
the interlayer insulating layer 160, to be adjacent to the light
emission control TFT T6. The lower power supply line 177 may be
electrically connected to the operation control source region 133e
of the operation control active layer ACTe via the contact hole 165
formed in the first insulating layer 141, the second insulating
layer 142, and the interlayer insulating layer 160. The second
inorganic insulating layer 172 may be arranged over the interlayer
insulating layer 160 and cover the first conductive layer 175 and
the lower power supply line 177. The first organic insulating layer
171 may be arranged over the second inorganic insulating layer 172.
The second inorganic insulating layer 172 and the first organic
insulating layer 171 may continuously extend from above the first
conductive layer 175 to above the lower power supply line 177, and
may directly contact the first conductive layer 175 and the lower
power supply line 177.
The second inorganic insulating layer 172 may include an inorganic
material such as silicon oxide, silicon nitride, and/or silicon
oxynitride and may cover the first conductive layer 175 and the
lower power supply line 177, thereby protecting the metal forming
the first conductive layer 175 and the lower power supply line 177
from being oxidized. The first organic insulating layer 171 may
include an organic material such as acryl, benzocyclobutene (BCB),
polyimide, or hexamethyldisiloxane (HMDSO), may perform a function
to planarize a surface by removing a step formed between the first
conductive layer 175 and the lower power supply line 177. According
to an embodiment, the second inorganic insulating layer 172 may be
formed of silicon nitride (SiN.sub.x), and the first organic
insulating layer 171 may be formed of polyimide (PI).
The second conductive layer 179 and the upper power supply line 178
are arranged over the first organic insulating layer 171. The
second conductive layer 179 and the upper power supply line 178 may
be formed of, for example, aluminum (Al), platinum (Pt), palladium
(Pd), silver (Ag), magnesium (Mg), gold (Au), nickel (Ni),
neodymium (Nd), iridium (Ir), chromium (Cr), lithium (Li), calcium
(Ca), molybdenum (Mo), titanium (Ti), tungsten (W), and copper
(Cu), in a single layer or as multilayers, depending on factors
such as conductivity. For example, the second conductive layer 179
may be a stacked structure of a first layer 179a including titanium
(Ti), a second layer 179b arranged on the first layer 179a and
including aluminum (Al), and a third layer 179c arranged on the
second layer 179b and including titanium (Ti). The first conductive
layer 175 may also have the same structure as the second conductive
layer 179. However, the present inventive concept is not limited
thereto, and, depending on factors such as conductivity, the first
conductive layer 175 and the second conductive layer 179 may be
formed of various types of metals or metal compounds.
The second inorganic insulating layer 172 may include a third
opening 172h3 exposing a part of the first conductive layer 175.
The first organic insulating layer 171 may include the first
opening 171h1 exposing a part of the first conductive layer 175
that is exposed by the third opening 172h3, The second conductive
layer 179 may be electrically connected to the first conductive
layer 175 via the first opening 171h1 and the third opening 172h3.
The first opening 171h1 and the third opening 172h3 may be
interpreted to be the contact hole 183 that connects the first
conductive layer 175 and the second conductive layer 179. A width
L1 of the first opening 171h1 may be greater than a width L3 of the
third opening 172h3. In other words, as illustrated in FIG. 3, an
area of the first opening 171h1 is greater than that of the third
opening 172h3. The third opening 172h3 may be arranged inside the
first opening 171h1.
The second inorganic insulating layer 172 may further include a
seventh opening 172h7 exposing a part of the lower power supply
line 177. The first organic insulating layer 171 may further
include a sixth opening 171h6 exposing a part of the lower power
supply line 177 that is exposed by the seventh opening 172h7. The
upper power supply line 178 may be electrically connected to the
lower power supply line 177 through the sixth opening 171h6 and the
seventh opening 172h7. In other words, as the power supply lines
177 and 178 are configured to include the lower power supply line
177 and the upper power supply line 178 that are arranged in
different layers, resistance of the power supply lines 177 and 178
may be reduced while occupying a reduced space. The sixth opening
171h6 and the seventh opening 172h7 may be interpreted to be the
contact hole 187 that connects the lower power supply line 177 and
the upper power supply line 178.
The upper power supply line 178 may include a protruding area 178a
(see FIG. 2) that protrudes toward an area overlapping the second
storage conductive plate 127 (see FIG. 2) in plan view. The upper
power supply line 178 is electrically connected to the lower power
supply line 177 via the contact hole 187 formed in the first
organic insulating layer 171 and the second inorganic insulating
layer 172. The lower power supply line 177 is electrically
connected to the second storage conductive plate 127 via the
contact hole 168 formed in the interlayer insulating layer 160.
Consequently, the upper power supply line 178 may be electrically
connected to the second storage conductive plate 127. In other
words, the protruding area 178a of the upper power supply line 178
may function as one conductive plate with the second storage
conductive plate 127. According to the above configuration, the
protruding area 178a may function as the storage capacitor Cst with
the first conductive plate 125a (see FIG. 2, and thus the
capacitance of the storage capacitor Cst may be stably provided.
The storage capacitor Cst is formed to overlap, in plan view, the
driving TFT T1 that occupies a large area in a pixel. Accordingly,
a space occupied by the storage capacitor Cst in a pixel may be
minimized, but the storage capacitor Cst may have a high
capacitance.
The first inorganic insulating layer 182 covering the second
conductive layer 179 and the upper power supply line 178 may be
arranged over the first organic insulating layer 171. The first
inorganic insulating layer 182 may include an inorganic material
such as silicon oxide, silicon nitride, and/or silicon oxynitride.
As the first inorganic insulating layer 182 covers the second
conductive layer 179 and the upper power supply line 178, the metal
forming the second conductive layer 179 and the upper power supply
line 178 may be protected from being oxidized. For example, the
first inorganic insulating layer 182 may include silicon nitride
SiN.sub.x. The first inorganic insulating layer 182 may include the
second opening 182h2 arranged around the second conductive layer
179. The second opening 182h2 may correspond to a space between the
second conductive layer 179 and the upper power supply line 178. In
other words, the first inorganic insulating layer 182 may include a
first region covering the second conductive layer 179 and a second
region covering the upper power supply line 178 and spaced apart
from the first region. The first region may directly contact the
second conductive layer 179, and the second region may directly
contact the upper power supply line 178.
When the conductive layer such as the second conductive layer 179
and the upper power supply line 178 arranged over the first organic
insulating layer 171 is lifted, a crack may be generated in the
first inorganic insulating layer 182 covering the conductive layer.
When the first inorganic insulating layer 182 does not include the
second opening 182h2, outgas generated from the first organic
insulating layer 171 may be intensively discharged through the
cracks generated in the first inorganic insulating layer 182 toward
the second organic insulating layer 181. In this case, an
agglomeration may be formed in the second organic insulating layer
181 due to the intensive discharge of the outgas and develop into a
progressive dark spot, thereby causing a pixel defect. However, the
first inorganic insulating layer 182 according to the present
embodiment may include the second opening 182h2 exposing the first
organic insulating layer 171, and thus, the outgas generated from
the first organic insulating layer 171 may be smoothly discharged
through the second opening 182h2 without concentrating in a
particular area. Accordingly, the pixel defect due to the
generation of dark spots may be removed or reduced.
The second organic insulating layer 181 is arranged over the first
inorganic insulating layer 182. The first organic insulating layer
171 and the second organic insulating layer 181 may directly
contact each other via the second opening 182h2 included in the
first inorganic insulating layer 182. In other words, the second
organic insulating layer 181 may directly contact the first organic
insulating layer 171 between the first region and the second region
of the first inorganic insulating layer 182. The second organic
insulating layer 181 may include an organic material such as acryl,
benzocyclobutene (BCB), polyimide, or hexamethyldisiloxane (HMDSO),
and may be formed of, for example, polyimide. The second organic
insulating layer 181 contacts the first inorganic insulating layer
182, and may be separated from the second conductive layer 179 and
the upper power supply line 178 by the first inorganic insulating
layer 182.
The first inorganic insulating layer 182 may include a fourth
opening 182h4 that exposes a part of the second conductive layer
179. The second organic insulating layer 181 may include a fifth
opening 181h5 that exposes a part of the second conductive layer
179 exposed by the fourth opening 182h4. A width L5 of the fifth
opening 181h5 may be greater than a width L4 of the fourth opening
182h4. In other words, as illustrated in FIG. 3, an area of the
fifth opening 181h5 is greater than that of the fourth opening
182h4, and the fourth opening 182h4 may be arranged inside the
fifth opening 181h5.
The pixel electrode 191 of the OLED may be electrically connected
to the second conductive layer 179 via the fourth opening 182h4 and
the fifth opening 181h5. The fourth opening 182h4 and the fifth
opening 181h5 may be interpreted to be the contact hole 185 that
connects the second conductive layer 179 and the pixel electrode
191.
The OLED including the pixel electrode 191, an intermediate layer
192 arranged over the pixel electrode 191 and including a
light-emitting layer, and a counter electrode 193 arranged over the
intermediate layer 192 is arranged over the second organic
insulating layer 181. The pixel electrode 191 may be electrically
connected to the light emission control drain region 135f of the
light emission control active layer ACTf through the second
conductive layer 179 and the first conductive layer 175.
The pixel electrode 191 may be formed to be a transparent or
semi-transparent electrode or a reflective electrode. When the
pixel electrode 191 is formed to be a transparent or
semi-transparent electrode, the pixel electrode 191 may include a
transparent conductive layer. The transparent conductive layer may
include at least one of indium tin oxide (ITO), indium zinc oxide
(IZO), zinc oxide (ZnO), indium oxide (In.sub.2O.sub.3), indium
gallium oxide (IGO), and aluminum zinc oxide (AZO). In this case,
the pixel electrode 191 may further include a transflective layer,
in addition to the transparent conductive layer, to improve light
transmission efficiency. The transflective layer may include at
least one of Ag, Mg, Al, Pt, Pd, Au, Ni, Nd, Ir, Cr, Li, Ca, and Yb
and may be formed in a thin film of several to tens of nanometers.
When the pixel electrode 191 is formed to be a reflective
electrode, the pixel electrode 191 may include a reflective film
formed of Ag, Mg, Al, Pt, Pd, Au, Ni, Nd, Ir, Cr, and a compound
thereof and a transparent conductive layer arranged above and/or
under the reflective film. The transparent conductive layer may
include at least one of ITO, IZO, ZnO, In.sub.2O.sub.3, indium
oxide, IGO, and AZO. However, the present inventive concept is not
limited thereto, and the pixel electrode 191 may be formed of
various materials. Also, the structure of the pixel electrode 191
may be variously modified to, for example, a single layer or as
multilayers. Although not illustrated in the drawings, a pixel
defining film (not shown) including an opening that exposes at
least a part of the pixel electrode 191 may be arranged over the
pixel electrode 191.
The intermediate layer 192 arranged over the pixel electrode 191
may include a light emitting layer. The intermediate layer 192 may
further include at least one of a hole injection layer (HIL), a
hole transport layer (HTL), an electron transport layer (ETL), and
an electron injection layer (EIL).
The intermediate layer 192 is not limited thereto and may have
various structures. The intermediate layer 192 may include an
integral layer over the pixel electrodes 191 arranged in the
respective pixels and may include a layer patterned to correspond
to each of the pixel electrodes 191.
The counter electrode 193 is formed integrally over a plurality of
pixels and may correspond to the pixel electrodes 191. The counter
electrode 193 may be formed to be a transparent or semi-transparent
electrode or a reflective electrode. When the counter electrode 193
is formed to be a transparent or semi-transparent electrode, the
counter electrode 193 may include at least one of Ag, Al, Mg, Li,
Ca, Cu, LiF/Ca, LiF/Al, MgAg, and CaAg and may be formed in a thin
film of several to tens of nanometers. When the counter electrode
193 is formed to be a reflective electrode, the counter electrode
193 may include at least one of Ag, Al, Mg, Li, Ca, Cu, LiF/Ca,
LiF/Al, MgAg, and CaAg. In this case, the counter electrode 913 may
be configured to have a high reflectance by sufficiently increasing
the thickness of the material. The structure and material of the
counter electrode 193 are not limited thereto, and various
modifications thereof are possible.
Although not illustrated in the drawings, a sealing member (not
shown) for sealing the OLED may be arranged over the counter
electrode 193. For example, the sealing member may be a thin film
encapsulation layer including an inorganic film and an organic
film.
In the organic light-emitting display apparatus according to the
above-described embodiment, since the second opening 182h2 exposing
the first organic insulating layer 171 is formed in the first
inorganic insulating layer 182 covering the second conductive layer
179, the outgas generated from the first organic insulating layer
171 is efficiently discharged through the second opening 182h2 so
that a pixel defect due to progressive dark spots may be removed or
reduced.
FIG. 5 is a schematic cross-sectional view of an organic
light-emitting display apparatus according to another embodiment.
FIG. 6 is a schematic plan view of a partial structure of the
organic light-emitting display apparatus of FIG. 5.
Referring to FIGS. 5 and 6, a TFT is arranged over a substrate 210,
and the TFT may include a gate electrode G and an active layer ACT
that includes a source region S, a drain region D, and a channel
region C connecting the source and drain regions S and D. To secure
insulation between the active layer ACT and the gate electrode G, a
first insulating layer 241 including an inorganic material such as
silicon oxide, silicon nitride, and/or silicon oxynitride may be
interposed between the active layer ACT and the gate electrode G.
In addition, a second insulating layer 242 including an inorganic
material such as silicon oxide, silicon nitride, and/or silicon
oxynitride may be arranged on the gate electrode G. An interlayer
insulating layer 260 may be arranged on the second insulating layer
242. The interlayer insulating layer 260 may include an inorganic
material such as silicon oxide, silicon nitride, and/or silicon
oxynitride. A buffer layer 211 including the inorganic material
such as silicon oxide, silicon nitride, and/or silicon oxynitride
may be interposed between the TFT and the substrate 210.
A first conductive layer 275 is arranged over the interlayer
insulating layer 260. For example, the first conductive layer 275
may be a stacked structure of titanium (Ti)/aluminum (Al)/titanium
(Ti). The first conductive layer 275 may be electrically connected
to the drain region D of the active layer ACT through a contact
hole formed in the first insulating layer 241, the second
insulating layer 242, and the interlayer insulating layer 260, to
be adjacent to the TFT. A second inorganic insulating layer 272
covering the first conductive layer 275 may be arranged over the
interlayer insulating layer 260. A first organic insulating layer
271 may be arranged over the second inorganic insulating layer
272.
The second inorganic insulating layer 272 may include silicon
nitride (SiN.sub.x) and cover the first conductive layer 275,
thereby protecting metal forming the first conductive layer 275
from being oxidized. The first organic insulating layer 271 may
include polyimide and may perform a function of planarizing a
surface by removing a step formed by the first conductive layer
275.
A second conductive layer 279 is arranged over the first organic
insulating layer 271. The second conductive layer 279 may be a
stacked structure of a first layer including titanium (Ti), a
second layer arranged on the first layer and including aluminum
(Al), and a third layer arranged on the second layer and including
titanium (Ti).
The second inorganic insulating layer 272 may include a third
opening 272h3 that exposes a part of the first conductive layer
275. The first organic insulating layer 271 may include a first
opening 271h1 that exposes the part of the first conductive layer
275 exposed by the third opening 272h3, The second conductive layer
279 may be electrically connected to the first conductive layer 275
via the first opening 271h1 and the third opening 272h3.
A first inorganic insulating layer 282 covering the second
conductive layer 279 may be arranged over the first organic
insulating layer 271. The first inorganic insulating layer 282 may
include an inorganic material such as silicon oxide, silicon
nitride, and/or silicon oxynitride and may cover the second
conductive layer 279, thereby protecting the metal forming the
second conductive layer 279 from being oxidized. For example, the
first inorganic insulating layer 282 may include silicon nitride
(SiN.sub.x). The first inorganic insulating layer 282 may include a
second opening 282h2 arranged around the second conductive layer
279, and the second opening 282h2 may be plurally provided.
Although FIG. 6 illustrates a case in which the second opening
282h2 is rectangular, the present inventive concept is not limited
thereto, and the second opening 282h2 may have various shapes such
as a circle, an oval, a pentagon, etc. Also, the number of the
second openings 282h2 is not limited.
When the second conductive layer 279 arranged over the first
organic insulating layer 271 is lifted, a crack may be generated in
the first inorganic insulating layer 282 covering the second
conductive layer 279 and the first organic insulating layer 271.
When the first inorganic insulating layer 282 does not include the
second opening 282h2, outgas generated from the first organic
insulating layer 271 may be intensively discharged toward a second
organic insulating layer 281 through a crack generated in the first
inorganic insulating layer 282. In this case, an agglomeration may
be formed in the second organic insulating layer 281 due to the
intensive discharge of the outgas develop into a progressive dark
spot, thereby causing a pixel defect. However, the first inorganic
insulating layer 282 according to the present embodiment may
include the second openings 282h2 exposing the first organic
insulating layer 271, and thus, the outgas generated from the first
organic insulating layer 271 may be smoothly discharged through the
second openings 282h2 without concentrating in a particular area.
Accordingly, the pixel defect due to the generation of dark spots
may be removed or reduced.
The second organic insulating layer 281 is arranged over the first
inorganic insulating layer 282. The first organic insulating layer
271 and the second organic insulating layer 281 may directly
contact each other through the second opening 282h2 included in the
first inorganic insulating layer 282. The second organic insulating
layer 281 may include an organic material such as acryl,
benzocyclobutene (BCB), polyimide, or hexamethyldisiloxane (HMDSO),
and may be formed of, for example, polyimide. The second organic
insulating layer 281 contacts the first inorganic insulating layer
282, and may be separated from the second conductive layer 279 by
the first inorganic insulating layer 282.
The first inorganic insulating layer 282 may include a fourth
opening 282h4 exposing a part of the second conductive layer 279.
The second organic insulating layer 281 may include a fifth opening
281h5 exposing the part of the second conductive layer 279 that is
exposed by the fourth opening 282h4. A pixel electrode 291 of the
OLED may be electrically connected to the second conductive layer
279 through the fourth opening 282h4 and the fifth opening
281h5.
The pixel electrode 291 is arranged over the second organic
insulating layer 281. A pixel defining film 295 covering an edge
area of the pixel electrode 291 may be arranged over the pixel
electrode 291. The OLED includes an intermediate layer 292 arranged
over the pixel electrode 291 exposed by the pixel defining film 295
and including a light-emitting layer and a counter electrode 293
arranged over the intermediate layer 292. The pixel electrode 291
may be electrically connected to the drain region D of the active
layer ACT through the second conductive layer 279 and the first
conductive layer 275.
In the organic light-emitting display apparatus according to the
above-described embodiment, since the second openings 282h2
exposing the first organic insulating layer 271 are formed in the
first inorganic insulating layer 282 covering the second conductive
layer 279, the outgas generated from the first organic insulating
layer 271 is efficiently discharged through the second openings
282h2 so that a pixel defect due to progressive dark spots may be
removed or reduced.
It should be understood that embodiments described herein should be
considered in a descriptive sense only and not for purposes of
limitation. Descriptions of features or aspects within each
embodiment should typically be considered as available for other
similar features or aspects in other embodiments.
While one or more embodiments have been described with reference to
the figures, it will be understood by those of ordinary skill in
the art that various changes in form and details may be made
therein without departing from the spirit and scope as defined by
the following claims.
* * * * *